DSA (Digital Subtraction Angiography) is known as one of imaging methods for blood vessels in an X-ray diagnostic apparatus. DSA is the technology to acquire subtraction image data between frames of X-ray image data before and after injecting a contrast agent into an object, for diagnosis. That is, X-ray image data are acquired before injecting a contrast agent as mask image data for generating subtraction image data. After that, X-ray contrast image data are acquired continuously with injecting the contrast agent. Then, DSA image data, which are also called subtraction image data, are generated for diagnosis by subtraction processing between the X-ray contrast image data and the mask image data.
On the other hand, not only CTA (computed tomography angiography) in an X-ray CT (computed tomography) apparatus and contrast MRA (magnetic resonance angiography) in an MRI (magnetic resonance imaging) apparatus but also non-contrast MRA as though contrast imaging had been performed are also well known. The contrast image data assume to include the non-contrast MRA data from now on. In a case of contrast imaging, non-contrast image data are acquired before injecting a contrast agent. Then, a contrast agent is injected, and contrast image data are acquired continuously. Thus, subtraction image data are generated for diagnosis, by subtraction processing between contrast image data and non-contrast image data.
Such subtraction image data can be generated as image data in which unnecessary anatomical structures in observation of a blood vessel have been removed. That is, diagnostic image data in which blood vessels enhanced by a contrast agent have been depicted selectively can be obtained.
An object of the present invention is to display images which are more useful for diagnosis of a blood vessel, especially for perceiving a blood flow pattern.